1. Field of the Invention
The present invention relates to a ratchet wrench, and more particularly to a rotation direction reversing gear setting mechanism on the head of a ratchet wrench for transferring strong torsion.
2. Description of Prior Art
In accordance with a conventional ratchet wrench 8, as shown in FIG. 8, the head 82 has a housing composing two interconnected circular recesses 811 and 812. The front recess 811 of the head 81 provides a space for holding a ratchet gear 821 of a socket driving member 82 therein. Behind it, the recess 812 holds two strip pawls 831 and 832 and a button toggle 85 therein. In the space between the outside edges of the strip pawls 831 and 832 and the inside wall of the circular recess 812, two conical springs 84 are respectively arranged. The button toggle 85 is set in a proper position between the inside edges of both strip pawls 831 and 832, for controlling which of the two strip pawls 831 and 832 will engage or disengage with the ratchet gear 821. In this case, as above-described, the transfer of all of the torsion force exerted on the handle of the ratchet wrench 8, depends on the engaging tooth of the ratchet gear 821 of the socket driving member 82 and one of the catching pawls 831 or 832, for generating a torsion moment on the socket driving member 82. Since the contacting surface between the strip pawl 831, 832 and the ratchet gear 821 is so small, the stress is too concentrated, distorting or even breaking the strip pawl, and damaging the tooth of the ratchet gear 821. Due to the small contact area, the generated torsion moment is so limited that changing the material, employing a harder carbide alloy, is the only way of improving the transfer of the torsion moment. The material cost and machining cost will therefore be increased, meanwhile, the production capacity and the output coefficient will be reduced. Even so, the improved value or torsion moment is very limited.